Sweet Itch (Queensland Itch) in Horses

Pam Hunter
by Pam Hunter
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Sweet itch is an allergic skin disease affecting sensitive horses and ponies from the bites of midges of the genus Culicoides. The allergic reaction develops at the site of the bite, and in the majority of cases skin lesions develop on the mane and tail and middle of the back, although sometime they are found under the belly, ears and head.

You will find your horse or pony intensely itching (called pruritus), which causes them to rub on anything and creates sores, sometimes with infection setting in. Control it can be a problem, with your main efforts focused on preventing the bites and treating the sores. Research indicated that this problem my run in families of horses showing the allergy.

Common Names for Sweet Itch (USA) are Queensland Itch (Australia), Summer Eczema and Seasonal Dermatitis. Culicoides flies, which breed in wet land, rivers, lakes and standing water are the cause of this irritation. Symptoms include weeping blisters; crusting, scabs and scaling; constant rubbing and biting; and potentially hair loss and skin damage.

Queensland Itch

Left: Here you can see clearly the sores caused by his scratching. There is little you can do to stop it, we use fly spray, treat the sore spots with a hydrocortizone cream, and keep him out of the pasture where this problem first developed.

Right: You can see that the tail head is missing some hair, and he has odd spots of missing hair on his flanks, armpits, face and scattered across his body.

Treatment

Your Vet may be able to use drugs (e.g. corticosteroids) to control the problem, but good insect control is your best defense.

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